Faulty brake pedal position sensor or switch; Sensor or switch out of adjustment, or its plunger or mounting damaged; Damaged, chafed or corroded wiring to the sensor, giving an open circuit; Loose, corroded or contaminated connector at the sensor or control module; Low supply or poor earth to the sensor, such as a blown fuse or weak battery; Fault in the control module or a related module that reads the sensor.

P057A

Brake Pedal Position Sensor A Circuit/Open.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
5: AreaVehicle speed, idle control and auxiliary inputs
7A: FaultThe specific fault in that area

What it means

P057A means the engine or powertrain control module has detected a fault in the circuit of brake pedal position sensor A, specifically an open circuit or a signal that is missing or out of range. The module cannot get a valid brake pedal position reading, so functions that rely on it may be limited. The exact sensor type (switch or analogue position sensor) and the functions that depend on it vary by vehicle.

Symptoms

Malfunction indicator lamp on, possibly with other warning lamps
Cruise control or adaptive cruise not working
Brake lights staying on, or not coming on when braking
Engine will not start, or stop-start is disabled
Reduced engine response or limited torque in some cases
Automatic gearbox shift lock or key interlock not releasing

Possible causes

Faulty brake pedal position sensor or switchlikely
Sensor or switch out of adjustment, or its plunger or mounting damagedlikely
Damaged, chafed or corroded wiring to the sensor, giving an open circuitlikely
Loose, corroded or contaminated connector at the sensor or control modulepossible
Low supply or poor earth to the sensor, such as a blown fuse or weak batterypossible
Fault in the control module or a related module that reads the sensorrare

How to diagnose

Read all stored and pending codes and freeze frame data, and note any related brake, cruise or stop-start codes
Check the brake lights work correctly and that the pedal moves freely with nothing trapped under it
Inspect the sensor, its mounting and the connector at the pedal for damage, looseness, moisture or corrosion
View live data for the brake pedal signal and confirm it changes smoothly when the pedal is pressed and released
Check the relevant fuses and the sensor's supply, signal and earth wires against the wiring diagram for your model
Test the wiring for continuity, shorts and high resistance with the connectors unplugged and the ignition off
Measure the sensor's output or resistance against the manufacturer's specification, as this varies by model
Check battery condition and charging voltage, as low voltage can upset sensor readings

How to fix

Repair or replace damaged wiring and terminals in the sensor circuit
Clean, secure or replace a corroded or loose connector
Replace the brake pedal position sensor or switch and set it up as the manufacturer specifies
Adjust or replace the mounting or plunger if the sensor is not sitting correctly
Restore a faulty supply or earth, and replace a blown fuse only after finding why it failed
Repair or replace the control module only after the wiring and sensor are proved good

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but first make sure the brake lights work properly, as a fault here can leave following drivers without warning. Get it checked soon, and avoid driving if the brake lights are not working or the car is behaving oddly.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.